1. Field of the Invention
The present invention relates to a power tool and an operating method for the power tool, especially to a gun-drill type power tool capable of storing and rapidly changing the tool bits and an operating method for rapidly changing the tool bits for the power tool.
2. Description of Related Art
Gun-drill type power tools in the prior art generally comprise electric drills, electric screwdrivers and percussive drills.
An electric screwdriver is a commonly used electric tool for tightening screws onto workpieces. When screws of different sizes are required to be tightened in use, different screwdriver bits may be replaced according to the difference of screw sizes, namely, remove the originally installed screwdriver bit and install a screwdriver bit of another size.
An electric drill is used to drill holes in workpieces. During the operation, the chuck clamps the bit and maintains rotary movement.
Generally, the user is required to make different types of operations, such as tightening of screws and drilling of holes. In this way, the user is required to get ready various electric tools or various tool bits, and make continual replacement in operation. In particular, under the condition where pre-punched hole is required before tightening a screw, it is required to keep replacement between the drill bit and the screwdriver bit, causing great inconvenience to the operator, not only leading to the trouble of replacing the tool bit, but also easy to lose the tool bit removed and put aside. Some manual tools can realize storage and rapidly changing of the tool bit, but the operation needs a lot of efforts due to the innate defect of the manual tool, namely small torque, which may result in the disadvantages of operator inclined to tiredness, low efficiency and unsuitability for being used as a professional tool in industrial application.
A US patent numbered U.S. Pat. No. 7,367,757B2 discloses a double-headed electric drill, comprising: a chuck for installing the screwdriver bit, and a chuck for installing the drilling bit, wherein the two chucks are disposed at 90 degrees to each other approximately and can rotate around the same pivoting point, the screwdriver function can be achieved by rotating the chuck for installing the screwdriver bit through 90° to make the head correspond to the main shaft, and then connecting the chuck with the main shaft; to change the drill function, separate the chuck for installing the screwdriver bit from the main shaft, and rotate reversely through 90° to make the chuck for installing the drilling bit correspond to the main shaft, and then connect the chuck with the main shaft to realize the drill function. As a result, many defects emerge, for instance, the need of two chucks, high precision requirement for the connecting structure between the two chucks and the main shaft, difficult manufacturing, and complicated overall structure, big volume and high cost of the double-headed electric drill.
A CN utility model patent numbered CN201086280Y discloses a multi-head electric tool, comprising a main body of the electric tool, and a multi-head runner structure, wherein the multi-head runner structure further includes a multi-head cartridge can capable of accommodating a plurality of tool bits, the multi-head cartridge can be connected with the main body of the tool axially in a sliding manner, and can rotate to select the required bit when it slides away from the main body of the tool. Thus, the operation is troublesome for the procedure of moving the multi-head cartridge can to separate the bit sleeve from the cartridge and then rotating the cartridge can to select the bit.
A CN invention patent numbered CN101563192B discloses a machine tool for rotatably driving tool bits, wherein the machine tool has a motor and a transmission device on which a tool change magazine is arranged. Tool chambers for accommodating bits are disposed on the tool change magazine. An operating slide member can axially move forward to pass through one of the tool chambers and drive the bit in the tool chamber into the tool clamp, or axially move backward to drive the bit in the tool clamp back to the tool chamber through the magnet arranged in the front end. An actuating assembly intended for making axial limitation to the operating slide member includes a supporting lever axially bracing the operating slide member. To change the bit, pressing the button can relieve the operating slide member from the axial limitation resulted by the supporting lever. Afterwards, moving the operating slide member can allow the operating slide member with the bit to exit from the tool clamp, and drive the bit to return to the tool chamber. After the operating slide member exits from the tool chamber, rotate the tool change magazine to select another bit. To make the bit enter into the tool clamp or return to the tool chamber, it is required to directly push or pull the operating slide member, so the machine tool must be of a considerable length, which expands the volume of the machine tool. However, with a compact and small-sized structure, the hand-holding is convenient, but configuration is bound to be complicated, still being a laborious tool. Moreover, when the machine tool works, the operating slide member is pressed against the tail end of the tool clamp, wherein the tool clamp can rotate, but the operating slide member can't, thus leading to a high slide friction between the operating slide member and the tool clamp, not only affecting work efficiency, but also speeding up the tool's friction, and shortening the service life of the tool.